The invention relates to an automatic testing apparatus for testing the circumferential spacing of gears, in which for the testing operation, the gear is rotationally driven by its own power source, via a slip coupling as needed, in one rotational direction and can be indexed from one measuring position to another, and in which a primary slide for the individual testing operations is displaceable on the frame of the apparatus by a drive mechanism substantially radially toward the gear and back away from it between stops which may be adjustable; provision is made for positioning the gear for the measuring operation and for measuring the spacing deviation of one tooth edge or flank (right or left) approachable in the vicinity of the pitch circle by means of a feeler disposed on the primary slide. Also, provision is made for the automatic insertion, continuing from one tooth gap to another, of the feeler into the measuring position and for retracting the feeler back out of this position, as well as for controlling the pick-up, emission and processing of the thereby coordinated measurement value. Furthermore, the invention relates to a method for testing the circular spacing, and, in a further development, to a method for measuring deviation and gear concentricity, tooth thickness deviation and tooth gap deviation on gears which can be indexed from one measuring position to another.
The testing apparatuses addressed above have varying designs and modes of operation in terms of the details thereof. In one case, the gear is rotationally connected with an incremental rotational drive means, by means of which the gear can be further divided in increments from one tooth gap to another by the spacing dimension ascertained without error, that is, by computer, which is the desired spacing dimension for the ideal case. A measuring feeler, preferably cooperating with an inductive transducer is pivotably supported on the primary slide and is retracted from the gear with the aid of the primary slide between the individual spacing steps brought about by the inductive transducer and, after the spacing step has been performed, is reinserted into the gear. For one testing revolution, the measuring feeler is in contact with one tooth flank, for example the left one, in the vicinity of the pitch circle for each measuring operation, and the deviation of this tooth flank from a zero-balance of the measuring feeler effective during a first measuring operation is ascertained and after processing is expressed by way of example by the electronic portion of the measuring apparatus. Once such a testing revolution has ended, the measuring feeler is shifted to the other tooth flank, that is, in this case, to the right tooth flank of the gear and again balanced to zero, the testing operation takes the same course as described above for one entire gear circumference.
In another measuring apparatus, the gear is driven via a slip coupling in one rotational direction, and two feelers are disposed on the primary slide, for example, one fixed feeler and one pivotable feeler cooperating with an inductive transducer. In the status where they are inserted into the gear, the feelers come into contact with the same tooth flanks (right or left) in adjacent tooth gaps, the flank at which the contact takes place being dependent on the rotational direction of the gear. Now in a first measuring operation the feelers are adjusted to the same circle in the vicinity of the pitch circle of the gear, which as a rule is effected by making them just touch, and the pivotable measuring feeler is then balanced to zero. Then with the aid of the primary slide, the feelers are retracted from the gear and the gear rotates under the effect of a drive mechanism until the feelers, being shifted by one tooth gap or space, are reinserted into the gear. Here the fixed feeler then holds the gear firmly counter to the action of the slip coupling, and the pick-up of the measurement value is effected by means of the pivotable feeler, being accordingly accomplished for the next spacing. Once the gear wheel has been tested in this manner over one revolution on one edge of the teeth, the feelers are then shifted to the other tooth flank, and the rotational direction of the gear is also reversed. The adjustment of the feelers and the course of the testing are then the same as described above.
In a third apparatus, the test object, again rotationally driven via a slip coupling, is firmly held by a detent device for the individual measuring operations, the detent device conventially being a ball head which is inserted into one tooth gap until it is in contact without play. On the other side of the primary slide, a transverse slide is disposed which can be displaced at a tangent to the gear counter to spring force. One fixed and one pivotable feeler, the latter cooperating with an inductive transducer, are again seated on the slide, in this case the transverse slide. Again in a first measuring operation, and with the gear held in place by means of the detent device, the two feelers are adjusted to the same circle in the vicinity of the pitch circle of the gear against one flank of the teeth, and the pivotable measuring feeler is again balanced to zero. The transverse slide in this case is shifted somewhat counter to the spring force acting upon it. For the next measuring operation, the detent device and the feelers are now retracted from the gear, and the gear rotates further by the amount of one spacing, driven by its drive mechanism, until the detent device dips into the next tooth gap and thus firmly holds the gear counter to the action of the slip coupling. The feelers are then driven into the gear teeth, and the spacing deviation is picked up via the pivotable measuring feeler and further processed in the measuring apparatus until it is transmitted. One complete testing revolution has ended, the feelers are newly adjusted against the opposite tooth flanks of two adjacent tooth gaps and balanced to zero, and the testing of the spacing deviation takes place during a new revolution of the gear.
Further details of these known apparatuses for testing spacing of gears will be explained later in detail in reference to the prior art drawings.
The known testing apparatuses have the disadvantage that two complete gear revolutions are required in order to ascertain errors in circumferential spacing, and furthermore the measuring feelers must be readjusted between the two revolutions from one tooth flank to the other tooth flank. This means high cost in terms of both time and money.
In order to measure deviation in gear concentricity, tooth thickness and tooth gaps, which are also of interest in assessing gear quality, a different testing apparatus is required. With it, in order to measure deviation in tooth gaps and gear concentricity, a ball-like measuring feeler is inserted into each tooth gap of the test object and the depth to which it is inserted at a given time is measured, providing information as to deviation from one tooth gap to another and finally as to the deviation in concentricity.
With respect to the deviations in tooth thickness, a fork-like measuring feeler is placed on each tooth of the gear wheel one after the other, and here again the depth of insertion or the deviation of the depth of insertion from an initially established zero balance is ascertained. Thus, in order to measure the three last-named values, at least further revolution of the gear and one further testing apparatus are required, still further increasing costs in time and money for testing gears beyond what was described above.